Re: [Gnu-arch-users] Re: tla on nfs only

[Aaron Bentley]

Stefan Monnier wrote:
> > For each file,
> > The first check tla does is stats against the revision library.  This is the
> > cheapest check it can do.  If the files are hardlinks of each other, the
> > working copy hasn't changed.
>
>
> In my world, this *never* happens, so it's a complete waste of time.

In my world, it's faster.

> Even if this works for you (i.e. you use --link), it still requires two
> stats per file, so it's still slower than the inode-sig check below.
> Sounds like a pessimization to me.

We had to do the stats anyway, to make sure that the file type and 
permissions haven't changed.  That code reuses the lstat results that 
are already necessary, so it's zero-cost.

> Also the work-tree inode-sigs need to be updated more often than just
> during `commit' so they're more effective..

I don't see the need here.  Are you frequently modifying and undoing 
large numbers of files?  Because for the 3-files-have-been-reverted 
case, it's just not worth it.

> Also the impact of not using a revlib because of an
> incorrectly-diagnosed corruption can be much more than just performance
> since rebuilding the revlib might require network access.

Yeah, but NFS requires network access too :-)

Perhaps what we need is a gen-inode-sigs command, so the user can assert 
 that the revlib is okay.  (presumably after an md5sum check or something)

Aaron

--
Aaron Bentley
Director of Information Technology
Panometrics, Inc.